There are widely known a pump device called booster blower or booster pump as a device that boosts gas such as fuel gas and oxygen to a desired pressure. A roots pump, a diaphragm pump, or the like is used for the pump device of this type. For example, Patent Document 1 below describes a diaphragm pump used as a booster blower for fuel gas in a fuel cell system.
In the case where the pump device is used in the fuel cell system, as a general method, a flow rate detector is provided on a suction side of the pump in order to stabilize the flow rate and a detection signal of this flow rate detector is used to control a motor of the pump. However, the flow rate detector takes high cost. In addition, a correct flow rate cannot be detected due to the influence of pulsation during low-flow rate operation, and hence the operation of the pump cannot be stably controlled.
In view of this, Patent Document 2 describes a fuel cell system in which an outside air temperature is detected and the rotation speed of the pump is corrected based on the detected temperature. With this, it is possible to control the operation of the blower without using the flow rate detector.
Patent Document 1: Japanese Patent Application Laid-open No. 2009-047084
Patent Document 2: Japanese Patent Application Laid-open No. 2007-234443